Professional DSP Alternatives

While I have no experience using the miniDSP, I do know that the value in a any proprietary programmable platform typically comes more from its application software development interface, and tools, than from its actual hardware. This is especially true when the application is being developed by an end user who isn’t an experienced expert with that product. Just something to consider besides the price and power of the hardware alone.
 
Many people on the forum have successfully used Behringer and dbx processors for their stereo 3-way systems. In fact a close copy of the dbx 260 was also sold as JBL DSC260 by the parent company Harman, for cinema applications. There's just no reason why it wouldn't work at home.

But note that dbx and Behringer only have IIR filtering and if you're looking to go further than that then you may want to look at something else.
 
The behringer at the moment is unobtainium. At the moment a used one is more than msrp. I'm pondering selling a couple I was using for my 4-way that I am almost ready to fully commit to the motu with a pi instead. Almost ashamed to say, but the "light show" of the DCX is just so much better than the motu, and that is the only thing holding me back from fully committing to the motu.